/* Test generating and verifying a DSA signature */
try {
/* generate a key pair */
KeyPairGenerator keyGen = KeyPairGenerator.getInstance("DSA");
keyGen.initialize(1024, new SecureRandom());
KeyPair pair = keyGen.generateKeyPair();
/* create a Signature object to use
* for signing and verifying */
Signature dsa = Signature.getInstance("SHA/DSA");
/* initialize the Signature object for signing */
PrivateKey priv = pair.getPrivate();
dsa.initSign(priv);
/* Update and sign the data */
FileInputStream fis = new FileInputStream(args[0]);
byte b;
while (fis.available() != 0) {
b = (byte) fis.read();
dsa.update(b);
};
fis.close();
/* Now that all the data to be signed
* has been read in, sign it */
byte[] sig = dsa.sign();
/* Verify the signature */
/* Initialize the Signature object for verification */
PublicKey pub = pair.getPublic();
dsa.initVerify(pub);
/* Update and verify the data */
fis = new FileInputStream(args[0]);
while (fis.available() != 0) {
b = (byte) fis.read();
dsa.update(b);
};
fis.close();
boolean verifies = dsa.verify(sig);
System.out.println("signature verifies: " + verifies);
} catch (Exception e) {
System.err.println("Caught exception " + e.toString());
}
